1. Field
The present disclosure relates to an improved acid-resistant Kluyveromyces marxianus and a strain that produces 3-hydroxypropionate with high efficiency prepared by using the same.
2. Description of the Related Art
3-hydroxypropionate (3-HP) is an organic acid. A calcium salt of 3-HP has a water solubility about one hundred times higher than that of a calcium salt of citric acid or malic acid and thus is useful in preventing scale in a boiler or an industrial facility. In addition, 3-HP is an important synthetic intermediate in several chemical processes. In particular, 3-HP is important in producing several chemicals and polymers including production of malonic acid by an oxidation reaction, production of a special-purpose polyester by an esterification with an alcohol, and production of 1,3-propanediol by a reduction reaction. In particular, 3-HP may be used as a precursor of acrylic acid, acrylic polymer, 1,3-propanediol, malonic acid, acrylamide, and others. For example, acrylic acid is used as a raw material for polymerization of a coating material, an adhesive, a detergent, and an absorbent. The market size of acrylic acid is about 8 trillion KRW in the world and about 140 billion KRW in Korea as of 2008.
Methods of preparing 3-HP may be classified as chemical methods and biological methods. Known chemical methods include a method of preparing 3-HP by using 1,3-propanediol as a starting material and palladium as a catalyst and a method of preparing 3-HP by using 3-hydroxypropionaldehyde in existence of palladium and platinum catalysts. In addition, a method of preparing 3-HP in which an ion exchange resin (Amberlyst 15) is used as a solid acid catalyst and a reaction is performed for 40 hours in a high pressure reactor by using acrylic acid as a starting material has been reported. The selectivity of this method of preparing 3-HP is 91% and the yield is 34%.
The biological method is to synthesize 3-HP by using a microorganism under high temperature and high pressure conditions. For example, reported biological methods of preparing 3-HP include a method of synthesizing 3-HP by using a Candidarugosa mutant (Candidarugosa KT8201) from acrylic acid, propionic acid, and propionaldehyde, a method of synthesizing 3-HP by using Alcaligenes faecalis M3A from acrylic acid, and a method of synthesizing 3-HP by using a Escherichia coli metabolic engineering technology from glucose. However, when a microorganism is used, the 3-HP productivity is low. Such a low productivity is a problem in producing 3-HP by using a biological process. In particular, as 3-HP is an acid, after a microorganism produces 3-HP over a certain level, the pH becomes too low and the microorganism is unable to produce more 3-HP.
Therefore, studies have continuously been conducted to find an appropriate and optimal microorganism to resolve the problem. One embodiment of the present invention provides a newly developed microorganism which is capable of surviving a low pH and a method of effectively producing 3-HP by using the same.